The present invention is generally in the field of ophthalmic lenses, including contact lenses and intraocular lenses, and relates to such lenses with reduced halo effects.
Halo effects are known as a glow or color light pattern that can be best observed when looking at a bright source in front of a dark background, for example a broad spot of light seen around a street light in the dark. This optical phenomenon is mainly caused by interaction of light with matter, and is enhanced due to diffraction of light when interacting with the eye, e.g. passing through the eye pupil, eye tissue, or any other diffraction of light caused by sharp edges or artificial diffraction structures, such as intraocular lens.
Techniques aimed at reducing the halo effects in lenses have been developed. For example, U.S. Pat. No. 6,557,998 discloses ophthalmic lenses, for example, intraocular lenses, contact lenses, corneal implant lenses and the like, having multifocal characteristics which provide beneficial reductions in at least the perception of one or more night time visual symptoms such as “halos”, and “glare or flare”. According to this technique, an intraocular lens having a baseline diopter power for far vision correction, has a near zone including an inner region having a substantially constant vision correction power greater than the baseline diopter power, and an additional near zone located outwardly of the near zone and having vision correction powers greater than the baseline diopter power and the near zone, and including a central plateau region having an inner end and an outer end and vision correction powers which increase progressively from the inner end to the outer end.